Infusion ports for the infusion and/or withdrawal of fluids from a patient are well-known, secured to the proximal end of an implanted catheter. These ports are typically used for drug infusion or small amounts of blood withdrawal, where large flows of fluid are not required. The ports are assemblies of a needle-impenetrable housing with a discharge port in fluid communication with the catheter and the reservoir within the port housing, and provide a subcutaneous self-sealing septum that defines an access site for multiple needle sticks through the covering skin tissue of the patient, through the septum and into the reservoir, without the need to continuously search for new access sites. Examples of such ports are disclosed, for example, in U.S. Pat. Nos. 4,704,103; 4,762,517; 4,778,452; 5,185,003; 5,213,574 and 5,637,102.
The septum conventionally includes a dome-shaped access surface into which the needle is to be inserted. The domed access surface rises upwardly at least as far as the surrounding periphery of the port housing, and conventionally such surface is domed so that a practitioner is easily able to locate the access port and particularly the septum access surface that is subcutaneously placed under the skin of the patient, by palpation. Also, conventionally, the surrounding periphery of the cap serves as a tactilely discernible ring indicating that the septum's access surface is inside thereof. Such palpation is disclosed particularly in U.S. Pat. Nos. 4,772,270 and 5,137,529, and in U.S. Patent Publication No. 2006/0224129 A1.
It is desired to provide a venous access port assembly that provides a more easily discernable needle target identification capability via palpation.